New Jersey Gov. Chris Christie speaks during a news conference on Jan. 9, 2014, at the Statehouse in Trenton, N.J.
(AP)

Federal officials are probing whether the New Jersey government improperly spent millions in U.S. taxpayer dollars as part of an ad campaign in the wake of Superstorm Sandy, a Democratic congressman said Monday.

The apparent probe comes as Gov. Chris Christie faces separate investigations over controversial road closures last year which documents suggest were politically motivated. But well before that scandal, Democrats had questioned the post-Sandy tourism ads, complaining that they featured Christie's image in the middle of a reelection campaign.

Rep. Frank Pallone, D-N.J., said Monday that the Office of the Inspector General at the U.S. Department of Housing and Urban Development has decided to "audit" the state government over the spending -- at his request.

"I commend the HUD Office of the Inspector General for investigating whether the state properly utilized taxpayer funds for this marketing campaign," Pallone said in a statement. "Working with my New Jersey colleagues, we had to fight hard to get the Sandy aid package passed by assuring others in Congress the funding was desperately needed and would be spent responsibly."

At issue is $25 million tabbed for a New Jersey marketing campaign in the wake of the devastating storm.

More On This...

Pallone, in his original August request for an investigation, questioned the bidding process and the content of the ads.

He claimed that the $4.7 million value of the contract with the winning firm was $2 million more than the next-lowest bid. Further, he raised concerns that the "winning bid proposed including Governor Chris Christie in the advertisements, while the lower cost proposal that was not selected did not."

Pallone reiterated those concerns on Monday.

Christie's office, though, defended the ads.

"The Stronger Than The Storm campaign was just one part of the first action plan approved by the Obama Administration and developed with the goal of effectively communicating that the Jersey Shore was open for business during the first summer after Sandy," spokesman Colin Reed said. "Federal agency reviews are routine and standard operating procedure with all federally allocated resources to ensure that funds are distributed fairly. We're confident that any review will show that the ads were a key part in helping New Jersey get back on its feet after being struck by the worst storm in state history."

The U.S. Department of Housing and Urban Development would not confirm or deny reports of the audit.

Christie and his government are facing mounting scrutiny following last week's revelations that close aides were involved in closing down two lanes of the busy George Washington Bridge last year, as an apparent act of political revenge.

Christie, though, has apologized and denied involvement. He fired his deputy chief of staff and sidelined his former campaign manager over the controversy.

That hasn't stopped state Democrats from pursuing their own investigations. Top Democrats in the state Assembly announced Monday that Assemblyman John Wisniewski would lead a newly formed "special investigatory committee," which has subpoena power, to look into the road closures.